With autoimmune diseases, the immune system is directed against the endogenous structures of the body. T-cells can play a role in identifying the endogenous structures as foreign to the body when not properly suppressed by regulatory T-cells. The cause of the failure of the regulatory T-cells to regulate the T-cells may be unknown. The loss of regulation can result in an inflammatory reaction on the humoral and cellular levels which, depending on the entity of the autoimmune disease, can lead to the damage of various organs.